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分别在江阴长江大桥1/4跨截面快车道、慢车道U肋对接焊缝处布设测点,测得该桥一天的应变历程曲线。基于雨流计数法以及Miner疲劳损伤累计准则,分析快、慢车道日损伤度分布规律,并提出了该桥U肋对接焊缝部位的日损伤分布模型,最后对U肋对接焊缝处的疲劳寿命进行评估。分析结果表明,快、慢车道出现损伤峰值的时间基本一致,但各峰值大小差异性较大,慢车道损伤峰值约为快车道损伤峰值的4.4倍;根据日损伤度分布模型得出的疲劳寿命拟合值与实测值吻合良好,可以应用于实际工程;大桥设计寿命约为慢车道U肋对接焊缝实测寿命的3.7倍,表明慢车道U肋对接焊缝的疲劳寿命远远不能满足设计要求,因此需要对慢车道U肋对接焊缝疲劳寿命给予特别关注。
The test points were laid at the fast lane and the slow lane U-rib butt weld of 1/4 cross-section of Jiangyin Yangtze River Bridge, and the strain curve of the bridge was measured. Based on the rain flow counting method and Miner fatigue damage cumulative criterion, the daily and damage distribution of fast and slow lanes are analyzed, and the daily damage distribution model of the U-rib butt weld is proposed. Finally, the fatigue of the U-rib butt weld Life expectancy is assessed. The analysis results show that the peak time of the fast and slow lanes is basically the same, but the difference of the peak values is quite large, the peak value of the slow lane is about 4.4 times of the peak value of the lane lanes, and the fatigue life based on the daily damage distribution model The fitted value is in good agreement with the measured value and can be applied to practical engineering. The designed service life of the bridge is about 3.7 times of the measured life of the U-rib butt weld in the slow lane, indicating that the fatigue life of the U-rib butt weld in the slow lane can not meet the design requirements , There is a need to pay special attention to the fatigue life of a slow-track U-rib butt weld.